rmore, the lumen may
be narrowed by swollen mucosa if the foreign body be of an irritant
nature. The signs vary with the degree of obstruction of the bronchus,
and with the consequent degree of interference with aeration and
drainage of the subjacent portion of the lung. We have three definite
types which show practically constant signs in the earlier stages of
foreign body invasion.

1. Complete bronchial occlusion.
2. Obstruction complete during expiration, but allowing the passage
of air during the bronchial dilatation incident to inspiration,
constituting an expiratory valve-like obstruction.
3. Partial bronchial obstruction, allowing to-and-fro passage of
air.

1. _Complete bronchial obstruction_ is manifested by limitation of
expansion, markedly impaired percussion note, particularly at the
base, absence of breath-sounds, and rales on the invaded side. An
atelectasis here exists; the air imprisoned in the lung is soon
absorbed, and secretions rapidly accumulate. On the free side a
compensatory emphysema is present.

2. _Expiratory Valve-like Obstruction_.--The obstructed side shows
marked limitation of expansion. Percussion is of a tympanitic
character. The duration of the vibrations may be shortened giving a
muffled tympany. Various grades and degrees of tympany may be noted.
Breath sounds are markedly diminished or absent. No rales are heard on
the invaded side, although rales of all types may be present on the
free side. In some cases it is possible to hear a short inspiratory
sound. Vocal resonance and fremitus are but little altered. The heart
will be found displaced somewhat to the opposite side. These signs are
explained by the passage of some air past the foreign body during
inspiration with its trapping during expiration, so that there is air
under pressure constantly maintained in the obstructed area. This type
of obstruction is most frequently observed when the foreign body is of
an organic nature such as nut kernels, beans, corn, seed, etc. The
localized swelling about the irritating foreign body completes the
expiratory obstruction. It may also be present with any foreign body
whose size and shape are such as to occlude the lumen of the bronchus
during its contracted expiratory phase. It was present in cases of
pebbles, cylindrical metallic objects, thick tough balls of secretion
etcetera. The valvular action is here produced most often by a change
in the size of the valve seat and not